Which of the following species is not stable?

Give reasons:
$(i)$ Conc. $HNO_3$ can be transported in aluminium container.
$(ii)$ $A$ mixture of dilute $NaOH$ and aluminium pieces is used to open drain.
$(iii)$ Graphite is used as lubricant.
$(iv)$ Diamond is used as an abrasive.
$(v)$ Aluminium alloys are used to make aircraft body.
$(vi)$ Aluminium utensils should not be kept in water overnight.
$(vii)$ Aluminium wire is used to make transmission cables.

Which are the various forms of silica?

Which of the following compounds is formed when chlorine gas reacts with dry slaked lime $Ca(OH)_2$?

Hydrolysis of which of the following does not occur?

$[SiO_4]^{4-}$ has a tetrahedral structure. Which silicate is formed by using three oxygen atoms?